• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.156-161
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• 2002

It depends on the joint configuration, dimensions and constraints on the joint whether the residual stress at the root of single-sided butt weld is tensile or not. Therefore, recommendation is generally made that high R ratio should be used in the fatigue test of this type of joint in order to prevent excessively long life caused by compressive residual stress. in this research, the residual stress profile in butt weld joint was obtained through compliance method, using successive extension of a slot and measurement of the variation of strain during the slot extension. The residual stress profile was firstly assumed to be the linear summation of Legendre polynomials up to 9th order excluding 0th and 1st order. Strain variation on the surface was measured while the slot was being extended by cutting to find out the 8 unknown coefficients of each polynomial tenn. The cut was made by the electric discharge machine. It was concluded that the residual stress near the surface stayed positive, however, it turned into the negative value as soon as it passed through 2 or 3 mm depth. Several fatigue tests were also carried out under zero stress ratio. Test results showed that fatigue life coincides well with the design cuive of butt joint in British Standards, which supports that it is tensile residual stress that exists near the weld root.

• 한국통신학회논문지
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• 제37권8C호
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• pp.711-720
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• 2012

본 논문에서는 운전자 졸음 인식 시스템의 구현 방법과 그에 따른 결과를 소개한다. 영상 입력 장치로는 시중에 판매되는 웹캠 카메라를 사용하였다. 얼굴 검출 방법으로는 Haar 변환 기법을 이용하였으며, 다양한 조명 환경에 강건하게 적응하도록 조명정규화를 수행하였다. 조명정규화를 거친 얼굴 영상은 특징값 추출에 용이하다. 조명정규화를 통한 눈 후보영역은 인체측정학 정보를 이용하여 후보 영역을 줄인 이후에 PCA와 Circle Mask의 혼합 모델을 적용했다. 위 방법을 통해 차량 내부의 복잡한 조명 환경 속에서 강건히 눈 영역을 추출한다. 검출된 눈 영역은 고해상도의 조명 정규화 영상과 간단한 연산을 통하여 졸음 여부를 판별한다. 졸음 상태가 1단계로 판단 될 경우에는 통합 모니터링 인터페이스에서 운전자에게 경고음을 울리며 2단계일 경우에는 CAN(Controller Area Network)를 통하여 안전벨트를 진동하게 함으로써 운전자에게 경고를 준다. 본 논문에서 제안하는 졸음 인식 시스템은 낮은 계산 복잡도를 만족하는 동시에 높은 인식률을 보여준다. 실험 결과 차량 내에서 97%의 인식률이 나타났다.

• 근관절건강학회지
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• 제10권2호
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• pp.188-202
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• 2003

The aim of study was to investigate the effects of 12 forms of Sun-style Tai-Chi for arthritis(TCA) on physical symptom(pain, tenderness, swelling fatigue, and blood pressure), physical function(balance, flexibility, grip strength) and social-psychological health status in osteoarthritis(OA) patients and rheumatoid arthritis(RA) patients. This study was done with one group pretest-posttest design. A total 21 arthritis patients(6 OA patient and 15 RA patient) participated in 60 minute session consisting of warm-up exercise 12-main movement including qigong, and cool-down exercise twice a week for 6weeks. Physiological and social-psychological variables were measured before and after TCA 12 form. The researcher who completed a Tai Chi workshop for exercise leaders in Australia and Seoul taught the Tai Chi movement step by step until the patient felt comfort enough to perform them correctly by themselves during the first 4 weeks. At the last 2 weeks, the subject perform 10-15set of these at a session with traditional music to help patients move in a slow tempo. TCA 12 forms program showed significant improvement in fatigue(p=0.039) of rheumatoid arthritis patient and pain(p=0.006), fatigue(p=0.013), tenderness(p=0.032), flexibility(rt arm up, p=0.014, If arm up, P=0.003), grip strength(rt hand, p=0.002, If hand, P=0.003) of osteoarthritis patients. With assessment by Arthritis Impact Measurement Scale 2 questionnaire(AIMS2), physical component(0.002) and social interaction(0.025) on osteoarthritis patients were significantly improved. Evaluation of the participants about TCA exercise noted that the exercise was fairly easy(23.6%), moderately difficult(57.1%), and fairly difficult(14.3%). Considering the result of this study, TCA exercise program was more effective in pain, tenderness, grip strength, flexibility, and physical and social interaction on osteoarthritis patients than rheumatoid arthritis patients. Tai-Chi for arthritis 12 form was an appropriate intensity exercise for osteoarthritis patients.

• 근관절건강학회지
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• 제7권2호
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• pp.269-280
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• 2000

This study was conducted to clarify the effect of physical ability, pain, fatigue, depression, sexual satisfaction, and spouse criticism on the sexual intrusiveness of rheumatoid arthritis(RA)women. The subjects of the study were 89 RA outpatients who visited the department of rheumatology of Dong-A University Hospital in Pusan from March 2000 to April, 2000. Pain & Fatigue via graphic rating scale, depression via CES-D(Center for Epidemiologic Studies -Depression) scale and physical ability via the Health Assessment questionnaire(HAQ) were assessed. Also we used both Sexual satisfaction scale(Kim, et al, 1997) to measure sexual satisfaction and Spouse criticism scale(Kraaimaat et al. 1996) to measure spouse criticism. The Intrusiveness rating scale which was derived from Arthritis Impact Measurement Scale(AIMS) was used to measure illness intrusiveness in sexuality. The relationships between the variables such as pain, depression, fatigue, physical ability, spouse criticism, sexual satisfaction and illness intrusiveness on sexuality were analyzed by Pearson correlation. As a result, pain & depression were significantly positively related to illness intrusiveness and physical ability & sexual satisfaction was significantly negatively related to illness intrusiveness. But these variables were interrelated. So hierarchical regression was performed to examine the relative contribution of pain, depression, physical ability, and sexual satisfaction with regard to intrusiveness of RA on sexuality. It revealed that pain, depression & sexual satisfaction predicted significantly illness intrusiveness on sexuality. Therefore it is very important to reduce pain and depression and to increase sexual satisfaction for reducing illness intrusiveness.

• 근관절건강학회지
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• 제14권1호
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• pp.26-32
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• 2007

Purpose: The purpose of this study was to determine if osteoarthritis patients would benefit in terms of pain, fatigue, difficulty with physical activity, joint stiffness, and flexibility of the joints from a structured self-help program. Method: This self-help program was carried out 2-3 hours once a week for 6 weeks in 2005-2006, and evaluated in one group pretest-posttest pre-experimental design. The subjects of this study who were diagnosed osteoarthritis were recruited at two different Community Health Centers in Kangwon. The subjects who agreed with the purpose of this study and participated both pretest and post-test were 55 patients. Mean age is 63.48 (9.48) years, mean duration of disease is 7.95 (7.66) years. The self-help program was consisted of weekly health contract, exercise, health education, group discussion, group counseling, and recreation. At every meeting, researcher and trained public health nurse evaluated the program, and prepared the next program. The measurement tools were pain rating scale (0-10), fatigue rating scale (0-10), Korean WOMAC (Western Ontario and McMaster University Osteoarthritis) Index, ruler, and goniometer. Results: At the completion of 6 weeks of self-help program, the subjects reported significantly less pain and difficulty with physical activity and more flexibility in both shoulder and knee joints compared to pretest. Conclusion: The self-help program would be helpful on pain, physical activity, and joint flexibility for arthritis patients.

• 대한인간공학회지
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• 제26권2호
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• pp.157-165
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• 2007

The Work-Related Musculoskeletal Disorders (WMSDs) can be occurred by various factors such as repetition, forceful exertions and awkward postures. Especially, occurrences of the WMSDs on the waist and lower limb are reported in workplaces, demanded standing postures for a long time, in service and manufacturing industry. The static and standing postures without movement for a long time increase work loads to the lower limb and the waist. Accordingly, anti-fatigue mat or anti-fatigue insole is used as a preventing device of the WMSDs. However anti-fatigue mats are limited in space and movement. In this study, multi-elastic insoles are designed and shown the effects of the workload reduction for a long time under the standing work. The foot pressures and EMG (Electromyography) are measured at 0 hour and after 2 hours by 6 health students in their twenties. The 6 prototype insoles are designed with three elastic (Low, Medium and High). These insoles are compared with no insole (insole type 7) as control group. The EMG measurement was conducted to waist (erector spinae muscle), thigh (vastus lateralis muscle) and calf (gastrocnemius muscle). The foot pressure is analyzed by mean pressure value and the EMG analysis is investigated through MF (Median Frequency), MPF (Mean Power Frequency) and ZCR (Zero Crossing Rate). The results of the foot pressure show that the multi-elastic insoles had smaller foot pressure value than that of no-insole. Moreover, Insole 2 and Insole 3 have the smallest increasing rate in foot pressure. The EMG results show that the multi-elastic insoles had smaller EMG shift value than that of no-insole in 2 hour, and then shift value shows the smallest value in Insole 2. Therefore, this study presents that the multi-elastic insoles have reducing effects of the work load for a long time standing work in both side of foot pressure and EMG.

• The Journal of Advanced Prosthodontics
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• 제13권5호
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• pp.304-315
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• 2021

PURPOSE. Esthetic expectations have increased the use of polyetheretherketone (PEEK) clasps as alternatives to Cr-Co in removable partial dentures (RPDs). The objective of this study was to evaluate the retentive force and dimensional change of clasps with different thickness and undercut made from PEEK by the thermo-mechanical fatigue. MATERIALS AND METHODS. PEEK clasps (N = 48) with thicknesses of 1 or 1.50 mm and 48 premolar monolithic zirconia crowns with undercuts of 0.25 mm or 0.50 mm were fabricated. Samples are divided into four groups (C1-C4) and were subjected to 7200 thermal aging cycles (at 5 - 55℃). The changes in the retentive force and dimensions of the clasps were measured by micro-stress testing and micro-CT devices from five measurement points (M1 - M5). One-way ANOVA, paired t-test, two-way repeated ANOVA, and post-hoc tests were used to analyze the data (P < .05). RESULTS. The retentive forces of C1, C2, C3, and C4 groups in initial and final test were found to be 4.389-3.388 N, 4.67 - 3.396 N, 5.161 - 4.096 N, 5.459 - 4.141 N, respectively. The effects of retentive force of all PEEK clasps groups were significant decreased. Thermo-mechanical cycles caused significant dimensional changes at points with M2, M4, and M5, and abraded the clasp corners and increased the distance between the ends of the clasp, resulting in reduced retentive forces (P^* = .016, P^* = .042, P < .001, respectively). CONCLUSION. Thermo-mechanical aging decreases the retentive forces in PEEK clasps. Increasing the thickness and undercut amount of clasps decreases the amount of dimensional change. The values measured after aging are within the clinically acceptable limits.

• Journal of Korean Biological Nursing Science
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• 제23권4호
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• pp.287-297
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• 2021

Purpose: This study aimed to evaluate the correlation and agreement of physical activity (PA) between data obtained from wearable Actigraph devices and self-reporting questionnaires, and to investigate the relationship between psychological state (depression, anxiety, and fatigue) and PA. Methods: A descriptive study was conducted using physical measurements and surveys. PA was measured through both the International Physical Activity Questionnaire (IPAQ) and the Actigraph GT3X+ device. The demographic characteristics of the subjects, as well as their depression, anxiety, and fatigue scores, were collected with structured questionnaires. The Spearman's rank correlation coefficient and the Bland-Altman plot method were employed. Results: Data from 36 healthy adults were analyzed. The overall levels of PA measured using the IPAQ and the Actigraph were 1,891.69 MET min/week and 669.96 MET/day, respectively. Total levels of PA did not show a significant correlation between the two measurement methodologies. However, the moderate-intensity PA resulting from the IPAQ scores showed a significant positive correlation with the light-intensity PA recorded by the Actigraph. The Bland-Altman plot analysis demonstrated that the levels of PA as measured by the two different methods did not match. In addition, PA measured using the Actigraph showed a significant negative correlation with depression and anxiety whereas PA measured using the IPAQ showed a significant positive correlation with fatigue. Conclusion: The conclusion of this study is that the data obtained from the subjective self-reporting questionnaire and the wearable Actigraph do not correlate or match in healthy adults. Future research should investigate the relationship between depression and PA intensity through the Actigraph, or other wearable devices equipped with smartphone apps.

• 방송공학회논문지
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• 제17권1호
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• pp.60-72
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• 2012

영화 아바타의 성공 이후, 3D 영화의 성공 사례가 계속 이어지지 못하고 있다. 3D 영상이 성공하기 위해 많은 것을 고려해야하지만, 특히 휴먼팩터 부분을 간과시한 결과가 아닌가 하는 주장이 제기되고 있다. 3D 영상이 시청자에게 어떠한 영향을 미치는지 이제 막 초기 연구가 실행되고 있는 상황에서 본 연구는 3D 영상 시청 후 시청자의 심리적 반응을 인지된 특성, 프레즌스, 시각 피로도 그리고 양안운동 지각을 통해 측정하고자 했다. 90명을 대상으로 한 실험연구 결과 첫째, 인지된 특성은 프레즌스에 영향을 미치고 인지된 특성의 세부 요인 중 실물감이 프레즌스에 영향을 미치는 것으로 나타났다. 둘째, 프레즌스의 경험정도가 높을수록 인지된 안구운동이 증가했지만, 시각피로도는 감소하였다. 이처럼, 프레즌스가 눈 움직임 지각과 시각피로도에 미치는 영향이 가지는 첫 번째 함의는 다음과 같다. 우리가 눈을 움직인다는 것은 우리가 미디어적인 도구로서 우리의 눈을 사용한다고 여기기보다는 눈과 함께 환경과 상호 작용하고 있다는 것이다. 따라서 콘텐츠에서 경험할 수 있는 상호작용의 요소들이 많아야 할 것이라고 추론할 수 있으며 이를 후속 연구를 통해 검증하는 것이 필요할 것이다. 다음으로는 프레즌스의 요인 중 시간 관여가 높아짐에 따라 시각피로도에 대한 지각이 감소한다. 반면 몰입 실재감이 증가함에 따라 시각피로도는 증가하게 되므로 콘텐츠 제작 시 몰입 실재감을 높이는 효과는 일정 수준이상이 되지 않도록 조절해야 할 것이다. 이를 위해 프레즌스에 영향을 미치는 인지된 특성변인 중 실물감 요인이 프레즌스의 세부요인별로 어떠한 영향을 미치는지, 프레즌스에 영향을 미치는 다른 변인은 무엇인지를 후속 연구를 통해 알아볼 필요가 있을 것이다.

• 비파괴검사학회지
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• 제37권2호
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• pp.99-105
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• 2017

Many composite materials are used in the aerospace industry because of their excellent mechanical properties. However, the nature of aviation exposes these materials to high temperature and high moisture conditions depending on climate, location, and altitude. Therefore, the molecular arrangement chemical properties, and mechanical properties of composite materials can be changed under these conditions. As a result, surface disruptions and cracks can be created. Consequently, moisture-impregnating defects can be induced due to the crack and delamination of composite materials as they are repeatedly exposed to moisture absorption moisture release, fatigue environment, temperature changes, and fluid pressure changes. This study evaluates the possibility of detecting the moisture-impregnating defects of CFRP and GFRP honeycomb structure sandwich composite materials, which are the composite materials in the aircraft structure, by using an active infrared thermography technology among non-destructive testing methods. In all experiments, it was possible to distinguish the area and a number of CFRP composite materials more clearly than those of GFRP composite material. The highest detection rate was observed in the heating duration of 50 mHz and the low detection rate was at the heating duration of over 500 mHz. The reflection method showed a higher detection rate than the transmission method.